Computing devices often utilize a graphics processing unit (GPU) to accelerate the rendering of graphics data for display. Such computing devices may include, e.g., computer workstations, mobile phones (e.g., so-called smartphones), embedded systems, personal computers, tablet computers, and video game consoles. Rendering generally refers to the process of converting a three-dimensional (3D) graphics scene, which may include one or more 3D graphics objects, into two-dimensional (2D) rasterized image data. A GPU may include a 3D rendering pipeline to provide at least partial hardware acceleration for the rendering of a 3D graphics scene. The 3D graphics objects in a scene may be subdivided by a graphics application into one or more 3D graphics primitives (e.g., points, lines, triangles, patches, etc.), and the GPU may convert the 3D graphics primitives of the scene into 2D rasterized image data. Therefore, in the specific context of GPU rendering, rendering may refer to the process of converting 3D graphics primitives that correspond to 3D objects in a graphics scene into 2D rasterized image data.
Rendering typically takes place with respect to a render target (e.g., a frame buffer), which is usually updated as each of the graphics primitives in the scene is rendered. Therefore, not only does the render target store the final 2D rasterized image data for a graphics scene, but the render target may also store intermediate data as the graphics scene is rendered. The 2D rasterized image data stored in the render target may include a plurality of pixels where each of the pixels includes color data, transparency data, and/or depth data. As each new primitive is rendered into the render target, the 2D rasterized image data of the new primitive is merged with the existing intermediate data that has already been stored in the render target for the previously rendered primitives.
To merge the data in the render target, the intermediate data typically needs to be read from the render target prior to writing the new data to the render target. Therefore, rendering may involve the performance of numerous read and write operations with respect to a memory that contains the render target, thereby resulting in high memory bandwidth usage.